FAQs - Smart Power Devices

Zero Current Switching (ZCS) ensures that a relay contact is closed at the zero crossing and opened at the precise moment when zero current flows through it. This has a number of advantages for smart power devices using relay switching techniques. With less potential harm from inrush currents, there is less wear on the relay itself and greater protection for connected switch mode power supplies (SMPS). There is also significantly reduced electromagnetic interference from repeated switching On/Off. Opening a relay contact when the current is zero is important for inductive loads (motors, transformers) but less so for capacitive loads including switch mode power supplies (SMPS) of the type found in computers, servers and IT network peripherals.

Zero Voltage Switching (ZVS) switches when the voltage is zero and is different to Zero Current Switching (ZCS) which switches when the voltage and current are both zero; referred to as the “zero-crossing” in a sinewave. ZVS is easier to implement into relay-based devices and whilst it works well for capacitive loads (switch mode power supplies). Zero voltage switching is not suitable for inductive loads including transformers and motors. Closing a relay contact when the voltage is zero is important for switching power supplies (switch mode power supplies: SMPS) of the type found in modern IT, computer and server loads.

An application program interface or API is way for separate software applications to exchange data and communicate between themselves. An API includes a set of routines, protocols and tools and specifies how these software components should interact i.e. when programming a graphical user interface (GUI).

SIP stands for Session Initiation Protocol and is used for internet telephony signalling including desk phones connected via Ethernet RJ-45 connections. SIP is also supported by most mobile Apps for making calls over a data connection and can be used over Ethernet or WiFi. The advantages of the SIP protocol is its simplicity. SOP uses the UDP port 5060 as standard but can also work on TCP/5060. See RFC3261 for more information on the protocol.

A URL API is a simple method for passing parameters as a part of a URL address starting with http or https. The address command can be entered into the address bar of a web browser including Google Chrome, FireFox, Apple Safari or Microsoft Internet Explorer or Edge.

M2M stands for Machine-2-Machine learning and is two machines communicating with each other or exchanging data, without human a interface or interaction. The interfacing can be via serial connection, powerline connection (PLC) or some form of wireless communications. M2M application programming interfaces (APIs) can include Telnet, URL API, SNMP/SNMPv3, XML, JSON, SIP, MQTT and MODBUS/TCP.

Lua is a basic programming language designed for use in embedded applications. It is a cross-platform language as the interpreter is compiled bytecode written in ANSI C and has a relatively simple C API. Lua is used for user scripts and supports a limited set of variables including Boolean values (true/false), numbers, strings and tables. In a compatible smart power device, a Lua script can be used to control power outlets and IP/LAN connectivity. A Lua script can run continuously or when trigged by an event to power sockets ON/OFF, send emails, receive and send ‘ping’ messages, download and parse XML/JSON files over http.